The present invention relates to a method for service provisioning a broadband modem. In particular, the present invention relates to a method for automatically provisioning a broadband communication service to a subscriber having a broadband modem
There is widespread interest among users of computers in faster access to content provided by internet service providers (xe2x80x9cISPsxe2x80x9d). In one sense, this interest appears to be driving the development of communication technologies that allow users to communicate with ISPs at higher and higher rates. A brief background of networking and a high speed communication service, known as Asymmetric Digital Subscriber Line (xe2x80x9cADSLxe2x80x9d) is set forth below as an introduction. In regard to related communication techniques, the entire contents of each of the following is incorporated herein by reference:
1. Integrated Local Management Interfaces (ILMI) 4.0, ADSL Forum, July, 1996
2. SNMP-based ADSL line MIB, Working Text Draft, ADSL Forum, Oct. 25, 1997
3. ILMI Based Service Provisioning for ADSL, ADSL Forum 98-025, Barcelona, Mar. 31, 1998.
4. Core Network Architectures for ADSL Access Systems, ADSL Forum 98-017, Barcelona, Mar. 31, 1998.
FIG. 1 shows a known technique for high speed communication service provisioning. A user 10 uses a telephone 20 to request a high speed service, such as ADSL, from a network service provider 30, such as by speaking with an operator 40 at a local central office location. A network service provider 30, also referred to as an NSP, is an access provider, in contrast to a content provider like an ISP. An engineer 50 at the central office then configures the network 60 for service in response to the user""s request. Next, the network service provider 30 informs the user 10 of network parameters to be used by the user 10 to configure an ADSL modem within the user""s personal computer 70. Content may be offered by an ISP 100 coupled to the network 60.
As shown in FIG. 1, the network 60 includes an Asynchronous Transfer Mode (xe2x80x9cATMxe2x80x9d) core 80 that is coupled to the computer 70 through a Digital Subscriber Line Access Multiplexer (xe2x80x9cDSLAMxe2x80x9d) 90. As defined in Newton""s Telecom Dictionary, 14th Expanded Edition, xe2x80x9cATM is a high bandwidth, low-delay, connection-oriented, packet-like switching and multiplexing technique.xe2x80x9d ATM and DSLAM device are well known to those skilled in the art of high speed communication.
A significant disadvantage to the technique shown in FIG. 1 is the involvement of the user 10 in configuring the ADSL modem in the personal computer 70. Communication devices, such as the personal computer 70, may be referred to herein more generally as the customer premise equipment (xe2x80x9cCPExe2x80x9d). Specifically, the requirement of user 10 involvement may discourage some user""s from requesting high speed service. There is also the danger of the user 10 misinterpreting the configuration information from the network service provider, or erroneously entering the configuration information. In addition, the involvement of the user 10 may cause the network service provider 30 to undertake the expense of providing technical support to the user.
Networks are collections of independent devices that communicate with one another over a shared physical connection, or network medium. Networks are often categorized as Local Area Networks (LAN) and Wide Area Networks (WAN).
Local area networks are usually confined to a specific geographic area, such as an office building. LANs, however, are not necessarily simple in design, and may link together hundreds of devices, including computers, printers, scanners and the like. The development of various standards for networking protocols has made possible the proliferation of LANs in organizations worldwide for business and educational applications.
Ethernet is a LAN networking protocol commonly utilized today. Ethernet typically utilizes a xe2x80x9cstarxe2x80x9d or xe2x80x9cspokexe2x80x9d topology, where each device of the LAN is connected to other devices via a central hub. In such a configuration, each device has its own private connection to the LAN and can be disconnected from the network without interfering with any other device""s connection.
Ethernet LAN technology was standardized by the Institute of Electrical and Electronics Engineers (IEEE) as the 802.3 specification entitled xe2x80x9cCarrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications.xe2x80x9d Initially, Ethernet technology used coaxial cable in a bus topology, however it has evolved to take advantage of new technologies such as twisted pair cabling (10 Base-T), fiber optics (10 Base-FL), and 100 Mbps operation (100 Base-X, or Fast Ethernet). The current standard is known as IEEE 802.3u, the contents of which are hereby incorporated by reference. One limitation of 10/100 Base-T is the requirement for xe2x80x9chome runxe2x80x9d cabling, i.e., each device is connected back to a central hub, as opposed to xe2x80x9cdaisy chainxe2x80x9d connections.
The Ethernet system consists of three basic elements: the physical medium; medium access control rules; and a packet format. The physical medium is used to convey Ethernet signals from one device to another. The medium access control rules are embedded in each Ethernet interface, and allow multiple devices to access the shared Ethernet channel. The Ethernet packet, or frame, consists of a standardized set of fields used to carry data over the system.
Interconnected LAN networks or individual users located in multiple physical locations are known as Wide Area Networks (WAN). The interconnections are performed via services such as dedicated leased phone lines, digital subscriber lines, dial-up phone lines, satellite links, and data packet carrier services. Wide area networking can be as simple as providing modems and a remote access server to allow remote users to dial in; or it can be as complex as linking hundreds of branch offices across the world using special routing protocols. Once type of WAN interconnection mechanism is Asymmetric Digital Subscriber Line.
Asymmetric Digital Subscriber Line (ADSL) is a communication system that operates over existing twisted-pair telephone lines between a central office and a residential or business location. It is generally a point-to-point connection between two dedicated devices, as opposed to multi-point, where numerous devices share the same physical medium. FIG. 1 illustrates a typical ADSL communication system.
ADSL supports bit transmission rates of up to approximately 6 Mbps in the downstream direction (to a subscriber device at the home), but only 640 Kbps in the upstream direction (to the service provider/central office). ADSL connections actually have three separate information channels: two data channels and a POTS channel. The first data channel is a high-speed downstream channel used to convey information to the subscriber. Its data rate is adaptable and ranges from 1.5 to 6.1 Mbps. The second data channel is a medium speed duplex channel providing bi-directional communication between the subscriber and the service provider/central office. Its rate is also adaptable and the rates range from 16 to 640 kbps. The third information channel is a POTS (Plain Old Telephone Service) channel. The POTS channel is typically not processed directly by the ADSL modemsxe2x80x94the POTS channel operates in the standard POTS frequency range and is processed by standard POTS devices after being split from the ADSL signal.
The American National Standards Institute (ANSI) Standard T1.413, the contents of which are incorporated herein by reference, specifies an ADSL standard that is widely followed in the telecommunications industry. The ANSI ADSL standard specifies a modulation technique known as Discrete Multi-Tone modulation.
Discrete Multi-Tone (DMT) uses a large number of subcarrier channels that are spaced close together. Each subcarrier may be modulated using a type of Quadrature Amplitude Modulation (QAM). Alternative types of subcarrier modulation include Carrierless Amplitude-Phase (CAP), Multiple Phase Shift Keying (MPSK), including Binary Phase Shift Keying (BPSK) and Quaternary Phase Shift Keying (QPSK), and Differential Phase Shift Keying (DPSK). In DMT systems using QAM, for example, the data bits are mapped to a series of symbols in the I-Q complex plane, and each symbol is used to modulate the amplitude and phase of one of the multiple tones, or subcarriers. Specifically, each symbol is used to specify the magnitude and phase of a subcarrier, where each subcarrier frequency corresponds to the center frequency of a xe2x80x9cbinxe2x80x9d associated with a Discrete Fourier Transform (DFT). The modulated time-domain signal corresponding to the sum of all the subcarriers can then be generated in parallel by the use of a well-known DFT algorithm, the Inverse Discrete Fourier Transform (IDFT).
The symbol period is relatively long compared to single carrier systems because the bandwidth available to each carrier is restricted. However, a large number of symbols is transmitted simultaneously, one on each subcarrier. The number of discrete symbols that may be distinguished on a single carrier, or within a bin, is a function of the noise level of the channel. Thus, the signal set, or constellation, for use with each subcarrier channel or bin may be determined based on the channel""s noise level within the relevant subcarrier frequency band.
Because the symbol period is relatively long and is followed by a guard band, intersymbol interference is a less severe problem in DMT systems than in single carrier, high symbol rate systems. Furthermore, because each subcarrier channel has a narrow bandwidth, the channel impulse response is relatively flat across each subcarrier frequency band.
The ANSI ADSL standard for DMT, ANSI T1.413, specifies 255 subcarrier channels or bins, each separated by approximately 4.3 kHz and each modulated at 4000 symbols per second. Each subcarrier can be independently modulated using known QAM techniques to achieve a maximum bit packing of 15 bits/Hz. This therefore allows up to approximately 60 kbps per tone. DMT transmission allows modulation and coding techniques to be employed independently for each of the bins.
In DMT systems, therefore, the modulation rate may be adaptively adjusted to line conditions for each of the bins. Many of the typical line impairments, including crosstalk, impulse noise and group delay, are frequency selective. Accordingly, bins having subcarrier frequencies that show greater impairments may carry lower bit rates, and bins that are less affected by the impairments may be assigned higher bit rates.
The bins overlap spectrally, but as a consequence of the orthogonality of the transform, if the distortion in the channel is mild relative to the bandwidth of a bin, the data in each bin can be demodulated with a small amount of interference from the other bins. For high-speed, wide-band applications, it is common to use a cyclic-prefix at the beginning, or a periodic extension appended at the end, of each symbol to maintain orthogonality. Because of the periodic nature of the FFT, no discontinuity in the time-domain channel is generated between the symbol and the extension. It has been shown that if the channel impulse response is shorter than the length of the periodic extension, bin isolation is achieved.
Many users, particularly small office and home users, are connected to their local central office by an ordinary analog subscriber loop, referred to herein as Plain Ordinary Telephone Service (POTS). POTS operates over numerous types of existing wiring layouts. Typically, the topology is a star configuration, combined with daisy chained connections for some phones. The type of wiring is also randomxe2x80x94twisted pair, untwisted, various gauges, various numbers of wires (with possible crosstalk)xe2x80x94which creates a wide variation in the channel characteristics. Furthermore, the topology changes from time to time as phones are connected, disconnected, etc.
Thus the channel characteristics in a residential application are very noisy and distorted, including phase distortion (group delay) and severe reflections (echoes from signals bouncing off unterminated wiring segments) and spectral dips due to unterminated wiring stubs. In addition, signals associated with the analog phone service include 48 vdc, and 100 volt ring signals. Ring signals are not zero-crossing switched, so high-frequency noise is produced. Any system operating over existing telephone wiring must contend with this environment.
While user friendly services do not insure success, complex and hard to use services may invite failure. On their own, ATM and ADSL are relatively complex technologies. Combined as a service to the home or small business office user, ATM and ADSL present a difficult challenge to the objective of user friendless. It would therefore be desirable to have a method for service provisioning a broadband modem.